RFR: Switch to using GitLab approvals instead of award_emojis

[Robin Westberg]

Later versions of GitLab allows Merge Request approvals even in the CE version, so we can start to use that instead of the award-emoji workaround used previously.

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Commit messages:
 - Switch to using GitLab approvals instead of award_emojis

Changes: https://git.openjdk.java.net/skara/pull/937/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=937&range=00
  Stats: 242 lines in 11 files changed: 2 ins; 221 del; 19 mod
  Patch: https://git.openjdk.java.net/skara/pull/937.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/937/head:pull/937

PR: https://git.openjdk.java.net/skara/pull/937